The present invention provides a vehicle traveling state determining apparatus including a camera which picks up an image of a road surface in a direction in which a vehicle is traveling, and zigzag state detecting section for determining a zigzag amount on the basis of the road surface image picked up using the camera, wherein the zigzag state detecting section is comprised of speed vector calculating section for calculating a speed vector of the road surface image by comparing a last road surface image picked up using the camera with a current road surface image picked up using the camera, and determining section for determining whether or not the vehicle is traveling in a zigzag line on the basis of the speed vector of the road surface image calculated by the speed vector detecting section.